C# delete from dbf where x=1 AND y=2

我需要使用OLEDB从dbf文件中删除行。为什么这个查询不起作用?数据库驱动程序出错。

m_query1 = "DELETE FROM tablename WHERE N_U='VS1' AND QMONTH=1";

但这工作得很好:

m_query1 = "DELETE FROM tablename WHERE N_U='VS1'";
m_query1 = "DELETE FROM tablename WHERE QMONTH=1";

p。错误:外部数据库驱动程序的意外错误(10019)

ps2。